Centrifuge assembly

ABSTRACT

A blood component separating device comprises a centrifuge bowl adapted for rotation about its axis in a centrifuge. The bowl defines an outer arcuate wall plus an inner circumferential wall, spaced from the outer wall, to define a arcuate slot adapted for receiving blood components. Access tubing is adapted for communication with the slot. Preferably, an elongated, flexible, collapsible inner liner is provided in the slot. Individual access tubing also may communicate with an elongated container interior between the ends of the elongated, collapsible container. Furthermore, a portion of the slot may define the shape of an outwardly extending spiral, to provide an increasing gravitational field upon fluids therein as the fluid moves along the slot.

This is a continuation of application Ser. No. 07/900,897 filed on Jun.18, 1992 now abandoned which is a division of U.S. application Ser. No.07/744,947, filed Aug. 14, 1991, now issued as U.S. Pat. No. 5,217,426,which is a continuation of U.S. application Ser. No. 07/660,710, filedFeb. 25, 1991 (now abandoned), which is a division of U.S. applicationSer. No. 07/463,694, filed Jan. 11, 1990 and now issued as U.S. Pat. No.5,006,103 which is a division of U.S. application Ser. No. 07/824,182,filed Aug. 12, 1977, and now issued as U.S. Pat. No. 4,934,995.

BACKGROUND OF THE INVENTION

Blood components are separated from units of human blood and utilizedfor separate therapy in patients. For example, blood plasma may beadministered without red cells. Also, the packed red cells can beadministered to a patient with a minimum of plasma or other suspendingsolution. Furthermore, platelets or white cells may be administered asspecific components. Also, platelet-poor plasma is another product fromblood utilized in various forms of therapy.

The invention of this application relates to a centrifuge which can beused to obtain, for example, separate portions of platelets, plasma(including platelet-poor plasma), other white cells, and packed redcells. The device of this invention can operate to process, in acontinuous operation, an unlimited amount of blood from a donor,processing the blood to separate and return the red cells to the donor,and to harvest, as desired, the white cells, platelets and plasma. Thecentrifuge bowl or container of this invention utilizes a radially thin,circumferential flow path for the blood and plasma being processed, toprovide a long, thin circumferential flow path in which a continuousprocess of separation may take place. As a result of this, a sweepingaction may take place over the thin, sedimented layer of the slightlyheavier particles such as the blood cells, to move the slightly lighterparticles (for example the white cells) downstream with respect to thered cells. This permits the use of sharply lowered G forces than iscustomarily used in conventional blood separation, with the slightlylighter cells being urged to move downstream more quicly than theslightly heavier red cells, to provide a more efficient cell separation.

Also, the thin, circumferential operating path provides a very shortsedimentation distance, no more than the restricted width of the path.This also provides the advantage that the centrifuge bowl container ofthis invention has a low blood volume so that a relatively small amountof blood is removed from the donor at any one time while at the sametime facilitating the sedimenting of red cells and protecting theplatelets from the known, undesirable effects of high G forces in excessof one thousand Gs.

Furthermore, the device of this invention permits the accumulation ofwhite cells and platelets during continuous operation, in which the redcells are sedimented along the circumferential path and then withdrawnfor reinfusion to the patient on a continuous or repeating basis. At thesame time, the white cells and/or platelets, which generally compriseless than one percent of the blood volume, can be accumulated during theoperation so that large amounts of white cells and platelets can beharvested in the single operation.

The above objectives are accomplished in the apparatus of this inventionwith minimal shear stresses being placed on especially the white cellsand platelets.

The invention of this application effectively provides an efficient,sterile means for obtaining blood components from a donor or fromreservoirs on a semi-automated basis, utilizing a disposable containerof novel configuration.

DESCRIPTION OF THE INVENTION

In accordance with this invention, a blood conponent separating devicecomprises a centrifuge bowl or chamber adapted for rotation about itsaxis in a centrifuge. The bowl defines an outer arcuate wall, and aninner circumferential wall spaced to define an annular arcuate slot,adapted for receiving blood components. The slot is adapted to containaccess tubing, and aperture means in the bowl permit the access tubingto pass out of the slot for connection with an exterior member.

In accordance with this invention, a portion of the slot adjacent theaperture means defines the shape of an outwardly extending signal. Theeffect of this is to provide an increasing gravitational field uponfluid therein as the fluid moves along the slot. This causes heavierparticles such as blood cells to settle outwardly, and then to slide tothe outward spiral end portion of the slot for collection. At the end ofthe spiral portion of the slot, a radially inwardly extending stepportion of the slot may be provided, whereby red blood cells positionedin the slot during centrifugation may collect at the outer end of thespiral portion.

Pockets can be provided in the outer arcuate wall defining the slot, forcollection of blood cells with access tubing communicating with saidpocket.

Also, a portion of the slot, positioned beyond the inwardly extendingportion from the spiral portion, may define a generally circular portionwhich is preferably positioned radially inwardly from the spiralportion, for the purpose of collecting platelets at a lower level ofcentrifugal force than the red cell collection portion.

A flexible, elongated, flat container or bag for blood components may bepositioned in the arcuate slot with the access tubing being incommunication with the container interior. The access tubing may bepositioned adjacent each end of the elongated, flat container forpassage of blood components through the slot within the container. Also,additional access tubing may communicate with the elongated, flatcontainer between the ends thereof for collection of centrifuged heaviercomponents such as red and white blood cells.

In one embodiment, the container bowl of this invention may processblood plasma to remove platelets which, upon centrifugation, collect onthe outer wall. Alternatively, the bowl of this invention may be used toprocess whole blood to collect both red and white blood cells andplatelets, with platelet-poor plasma passing out of the end of the bagpositioned within the circumferential slot. The bowl may also be used tocollect red blood cells alone.

Blood, plasma, or other liquid may be fed to one end of the elongated,flat bag for passage through the bag during centrifugation. Thecentrifuged liquid is then withdrawn from the other end of the bag,while red and white cells may be removed at various points intermediatealong the container as illustrated herein.

The tubing which is connected to the spinning, elongated, flat bag maybe connected to a stationary liquid source and a receptacle forprocessed liquid outside of the centrifuge by the use of a conventionalstructure making use of the principles of Adams U.S. Pat. No. 3,586,413,Khoja, et al. U.S. Pat. No. 3,986,442, and similar prior art utilizingthe feature of preventing the communication tubing from being twisted bymeans of the precise rotational relationship described in those patents.Accordingly, a conventional centrifuge can be adapted to receive thebowl of this invention, utilizing the rotational principles for thecommunication tubing described in the above-cited patents, in which oneset of ends of the communication tubing is spinning with the centrifugebowl and the other ends of the tubing are stationary, and connectedoutside of the centrifuge to a liquid source and a receptacle forprocessed liquids.

Referring to the drawings, FIG. 1 is a top plan view of an embodiment ofthe centrifuge bowl of this invention for the collection of both redcells and platelets.

FIG. 2 is a sectional view of the centrifuge bowl of this invention,taken along line 2--2 of FIG. 1.

FIG. 3 is an elevational view of a flexible, elongated, flat containerwhich may be utilized herein.

FIG. 4 is an enlarged, fragmentary elevational view of the container ofFIG. 3.

FIG. 5 is a detailed perspective view of an alternate technique forconnecting the tubing to the container, with portions broken away.

FIG. 6 is a longitudinal sectional view of the connection illustrated inFIG. 5.

FIG. 7 is a plan view of an alternate embodiment for the centrifuge bowlof this application.

FIG. 8 is a perspective view of third embodiment of the centrifuge bowlof this application, with one portion shown schematically.

Referring to FIGS. 1 and 2, centrifuge bowl or container 10 isillustrated, comprising a bowl member 12 and a cover 14 which isremovable from the bowl member, to define an arcuate channel or slot 16between cover 14 and bowl 12 as shown in FIG. 2. Typically, channel 16may be 50 mm. high, tapering from about 3.5 to 4.5 mm. (preferably 4mm.) in width at point 17 to about 12 mm. in width at approximatelypoint 19, and then narrowing again. Overall, channel 16 may be about 28inches in circumferential measurement.

As shown in FIG. 2, bowl member 12 defines a central aperture-definingsleeve 18, to permit attachment of the bowl to a centrifuge rotor forspinning of the container 10. Bowl member 12 comprises a disk-likeportion which terminates in a vertical arcuate wall 35. Cover member 14has a vertical wall portion 74 and may be seen to interfit and overliebowl member 12. The region formed between arcuate wall 35 and arcuatewall 74 of cover member 14 defines channel 16.

Referring to FIGS. 3 and 4, a flexible, elongated flat container or bag20 for placing in arcuate channel 26 is disclosed. Container or bag 20may be made out of a single piece of plastic, folded into U-shaped crosssection at the bottom, and sealed with R.F. (Radio Frequency) seals 22at the ends thereof, or by any other desired sealing technique. Also, anupper R.F. seal 24 is provided to seal an interior portion 26 of thecontainer in sterile manner from the exterior.

Tubings 28, 30 are provided at each end of the flexible, flat containeror bag to serve as an inlet and an outlet, tubing 28 being typicallyused as the inlet and 30 as the outlet. Upper RF seal 24 may slopeupwardly as shown for the purpose of encouraging the downstreammigration of air bubbles.

In the unsealed edge portion of bag 20, a plurality of perforations 32are provided to fit around pins 34, which project from the annular wall35 of bowl 12 inwardly to serve as a hanger means for bag or elongatedcontainer 20 when it occupies arcuate channel 16.

Bag 20 also defines intermediate connection pores for tubing 36 and 37which are positioned to communicate with sealed chamber portion 26 ofthe elongated bag or container. Ports for tubing 28, 30, and 37penetrate the seal 24 in conventional, sealed manner. The connectiondetails for tubing 36 will be described later.

Seal 39 defines a constricted portion inside of the interior of bag 26to divide it into two segments separated by narrow communicating channel41 as shown in FIG. 3. This permits, after use, the easy sealing andseparation of the bag at constricted channel 41 for harvesting ofplatelets in one segment thereof.

A detailed connection system for communication tubing 36 in theelongated bag or container 20 is shown in FIGS. 5 and 6. There, afragment of the elongated flat container 20 is shown. Container 20 maybe made of thin-walled, tubular plastic material, for examplepolyvinylchloride, among other materials. An aperture 38 is cut in theside wall of bag 20, and is covered by a filter screen 40. The tubing,for example communication tubing 36 (a portion of which is separatelyshown for clarity in FIG. 5) defines a plurality of perforations 42 inits side wall. The plurality of perforations 42 in the side wall of thetubing are adjacent the filter screen 40 to allow communication betweenthe tubing and the interior of fluid container 20. The ends of tube 36loop together to form in each case a single connecting 44 as shown inFIG. 3.

Outer wall member 46 tightly and sealingly surrounds the portion oftubing 36 containing perforations 42 and which may be R.F. sealed to theoutside wall of tubing 20. In particular, a seal line 48 runs aroundaperture 38 between outer wall member 46, tube 36 and the outside wallof bag 20, to provide a seal around aperture 38.

As shown in FIGS. 1 and 2, bag 20 is positioned in annular slot 16, withinlet port 38 projecting outwardly as shown through a space 50 in covermember 14. If desired, cover member 14 may be in two pieces, beingseparated at both space 50 and at diametrically opposed junction 32, toprovide a pair of generally semi-circular cover member sections 53, 55.

Bag or elongated container 20 is inserted into annular channel 16 in aclockwise manner with the inlet tubing 28 positioned at, the length ofbag 20 being so proportioned that it terminates adjacent the outlet slot54 in cover member 14, which provides room for the exit of tubing 30. Asstated before, pins 34 are placed through perforations 32 of bag 20 tosupport the bag in the annular slot 16. Bowl member 12 may typically beadapted to rotate in clockwise manner.

In a first segment 54 of arcuate slot 16 approximately defined betweenthe positions of tubes 28 ad 36, it will be noted that the respectiveslot-defining walls of bowl assembly 12 and cover 14 are proportioned tocause the slot to spiral outwardly. As shown in FIG. 1, outer wall 35 ofbowl member 12 defines the spiral shape. The spiral curve may be definedby the angle between radius 58 from the center of rotation to the outerwall 35 and the line 57 tangent to the defining curve of outer wall 35at the intersection with the radius. This angle is designated 56 and forincreasing or outwardly directed spirals may range in magnitude fromabout 80 to 85 degrees (specifically 821/2 degrees which is preferredfor a G field of about 200 to 220 G). This provides a graduallyincreasing centrifugal force on the blood or other fluid in annularchannel 16 during the centrifugal process as it flows along the lengthof container 20, which causes the red blood cells not only to migrate tothe radially-outward wall of elongated bag 20, but also to migrate in aclockwise manner to the end of spiral section 59 of arcuate channel 16.The resultant change in radius may preferably be about 0.2 to 1 cm.,specifically about 0.4 cm. Typically, the blood in first segment 54 ofslot 16 may be subjected to continuously changing G field as it movesalong and is confined by the spiral channel varying outwardly by aboutten percent of its radius. Generally, this invention may be used tocreate G fields of about 150 to 1,000 g, to obtain the desiredseparation and collection of red and white cells at low G fields toavoid the activation of platelets. The optimum angle 56 will change withdifferent G fields.

Alternatively, the angle 56 may be 83 degrees, and the G field is about285 G at the blood inlet to slot 16.

At the end of spiral section 59, the annular channel 16 defines aradially-inward step 60. Elongated container 20 is so positioned thatcommunication tubing 36 which loops to form connecting tube 44 ispositioned at step 60, projecting outwardly through aperture 62 in cover14.

The red cells are retained in the radially-outward pocket defined bystep 60, and may be withdrawn from elongated container 20 through tubing36. Aperture 38 and screen 40 are placed on the radially-outward lateralside of the elongated container 20, and collect red blood cells withgreat efficiency from the pocket defined by step 60.

After the inward step 60, arcuate channel 16 may define a generallycircular section 64, which terminates generally in a pocket 66 definedin the vertical arcuate wall 35 of bowl member 12. On centrifugation,elongated container 20 tends to distend into pocket 66, to provide acollection reservoir for white cells, as well as any red cells that havespilled over from the area defined by step 60. Communication tube 37 maybe positioned on bag 20 at this point to withdraw the white cells.

Transverse R.F. seal 39 in elongated container 20 is positioned adjacentinwardly positioned outlet 68, which comprises a pair of upstanding,radially inwardly directed walls 70 and a lateral aperture 71communicating through the annular upstanding wall 74 of cover member 14.

The portion 72 of container 20 which collects platelets is positioned ina section 76 of arcuate channel 16, which may define a generallycircular arc, containing the downstream end of the container 20 andoutlet tube 30. Generally, upon centrifugation, the platelets gentlyadhere to the outer wall of portion 72 of elongated container 20, andmay be resuspended and stored by agitation within the elongatedcontainer itself in a known manner until ready for use.

It has been found to be generally desirable for section 76 of thearcuate channel 16 to be positioned radially inwardly from at least thedownstream end of spiral portion 59 of the arcuate channel, to exert onthe platelets a somewhat lower centrifugal force than that which hasbeen found to be optimum for the collection of blood cells. By thismeans, an optimum centrifugal force (such as 200 to 220 G and preferablyno more than 400 G) for blood cells can be utilized, while at the sametime the platelets do not pack excessively upon the radially outer wallof container 20.

FIG. 7 is a plan view of a variant of the centrifuge bowl of thisinvention. As in the previous embodiment, bowl 80 includes a cover 82which cooperatively defines, with bowl 80, an arcuate channel 84.Channel 84 may be interrupted by slot 85 in cover 82 to define abeginning portion 86 and an end portion 88. Access tubing 90 and 92 arecarried by an elongated collapsible container 94, similar to bag 20 andpositioned within channel 84. Intermediate access tubings 96 and 98 arealso carried by bag 94.

As in the previous embodiment, portion 100 of the arcuate channel isoutwardly spirally-shaped for the same purpose as the previousembodiment, terminating in a step portion 102 to provide a pocket forthe entrapment of red cells. Preferably, the same slot configuration isused as in the previous embodiment, to provide the same order of varyingG field. The red cells may then be withdrawn through tubing 96.

Second segment 104 of channel 84 then leads to second step 106, whichmay be larger than the first step 102, and which is for the purpose ofcollecting white cells and any residual red cells that may have escapedthe previous pocket. The white cells may be withdrawn through tubing 98,connected with container 94.

Third segment 108 of the arcuate channel 84, containing bag 94, then maydefine a circular arc which is positioned radially inwardly of theentire red cell separating portion 100 of arcuate channel 84, to reducethe G field for platelet separation by collection on the outer wall ofbag 94, for example a G field of 120 to 125 G.

After cell separation operations are completed, bag 94 is removed, andmay be R. F. sealed to close the bag interior and then severed at area110, for example, for separation of the platelet-containing portion 108of the bag for storage, if desired.

As short separation bag may also be used, turning into and terminatingat slot 111, for the separation only of red cells and plasma. The outlettubing then leads from a radially-inward portion of bowl 80.

FIG. 8 is a perspective view of another bowl in accordance with thisinvention. In this embodiment, no cover is used, but a pair ofelongated, flexible bags 112, 114, of construction generally similar tobag 20, are provided in a pair of arcuate 116, 118 defined in a bowl120.

As in the previous embodiments, a central aperture is defined by sleeve122, provided for fitting upon a centrifuge spindle for rotation.

Inlet tubing 124 is connected to one end of bag 112, being supported byradially inwardly positioned walls 126. In this embodiment, slot 116defines a radially-inward end portion 128, to permit the bag 116 to turnradially inwardly, and then to extend in the circumferential directionthrough the main portion of slot 116.

A first pocket 130 is defined in the outer surface of slot 116, to serveas an initial red cell collecting pocket. Tubing 132 is positioned onbag 112, to be in communication with the bag interior adjacent thepocket 130, to remove collected red cells. Bag 112 and slot 116terminate at second pocket 134, from where tubing 136 (shownschematically) communicates between bag 112 and a conventional bloodpump 138, for example a roller pump for propelling blood through thesystem during centrifugation.

Downstream from roller pump 138, tubing 140, which is an extension oftubing 136, communicates with an end of the second bag 114, residing inslot 118 for collection of platelets in bag 114. The resultingplatelet-poor plasma is then removed from the other end of bag 114through tubing 142.

This arrangement eliminates the need for cutting the bags by providingseparate, elongated, flexible, collapsible bags for blood cellcollection and for the platelets.

White cells will also tend to collect in pocket 134. The entrance oftubing 136 may be positioned only at the top of the bag and at arelatively radially-inward position, if desired, so that the white cellsare retained in pocket 134. Otherwise, other appropriate means forcollection of the white cells, as in the previous embodiments, may beutilized if desired.

Slot 116 may spiral outwardly, if desired, as in the previousembodiments, or may define a circular arc about the axis of rotation.

The above has been offered for illustrative purposes only, and is notintended to limit the invention of this application, which is as definedin the claims below.

That which is claimed is:
 1. A centrifuge assembly for processing asuspension including at least one cell component, said assemblycomprising:a rotor; a first arcuate processing channel segment definedin said rotor for performing a separation function, said channel segmentbeing defined by a pair of spaced-apart rigid walls, and having a heightsubstantially greater than its width along a substantial length of saidchannel; a second arcuate processing channel segment, separate from saidfirst segment, defined in said rotor for performing another separationfunction, said channel segment being defined by a pair of spaced-apartrigid walls, and having a height substantially greater than its widthalong a substantial length of said channel segment; and fluidcommunication means extending between said first and second arcuatesegments for withdrawing at least a portion of the suspension from oneof said channel segments and for introducing it into the other of saidchannel segments.
 2. A centrifuge assembly in accordance with claim 1wherein the length of each of said channel segments is greater than itsheight.
 3. A centrifuge assembly in accordance with claim 1 wherein oneof said channel segments includes a generally circular portion.
 4. Acentrifuge assembly in accordance with claim 1 wherein one of saidchannel segments includes a generally spiral-like portion.
 5. Acentrifuge assembly in accordance with claim 1 wherein each of saidchannel segments comprises a separate disposable plastic containerlocated between said rigid walls of said channel.
 6. A centrifugeassembly in accordance with claim 5 wherein said separate containers aredefined by two plies of thin-wall flexible plastic material sealedtogether to define said two separate containers and a flow pathcommunicating therebetween.
 7. A centrifuge assembly in accordance withclaim 5 wherein said fluid communication means comprises tubing attachedat one end to one of said containers and attached at the other end tothe other of said containers.
 8. A centrifuge assembly in accordancewith claim 5 wherein at least one of said containers is defined by twoplies of thin-wall flexible plastic material sealed together to define acontinuously tapered height along a portion of one said container.
 9. Acentrifuge assembly in accordance with claim 5 wherein at least one ofsaid containers further comprises fluid-connection means associated withsaid container for removing a suspension component therefrom, said fluidconnection means comprising:means defining an aperture in saidcontainer; means defining a filter covering said aperture; and a fluidconduit communicating with the interior of said container through saidfilter means.
 10. A centrifuge assembly in accordance with claim 9wherein said filter means comprising a filter screen and said fluidconduit comprising a tube attached to said container and having aplurality of perforations therein disposed in direct communication withsaid filter screen, said fluid conduit comprising a tube extending fromopposite sides of said aperture and looping together to provide a singleconnect tube.
 11. A centrifuge assembly in accordance with claim 1wherein the suspension comprises blood, and said channel segmentscontains a quantity of blood which is relatively small compared to thevolume of blood in a human donor.
 12. A centrifuge assembly forprocessing a suspension including at least one cell component, saidassembly comprising:a rotor; a first arcuate processing channel segmentdefined in said rotor for performing a separation function; a secondarcuate processing channel segment, separate from said first segment,defined in said rotor for performing another separation function; fluidcommunication means extending between said first and second arcuatesegments and being adapted for cooperation with flow control means forwithdrawing at least a portion of said suspension from one of saidchannel segments and for introducing it into the other of said channelsegments; and flow control means cooperatively associated with saidfluid communication means for controlling the withdrawal of the portionof suspension from one of said channel segments and the introduction ofsuch portion into the other of said channel segments.
 13. A centrifugeassembly in accordance with claim 12 wherein one of said channelsegments includes a generally circular portion.
 14. A centrifugeassembly in accordance with claim 12 wherein one of said channelsegments includes a generally spiral-like portion.
 15. A centrifugeassembly in accordance with claim 12 further comprising a disposableplastic suspension-receiving container disposed between said rigid wallsof said channel.
 16. A centrifuge assembly in accordance with claim 15wherein said container comprises two plies of thin-wall flexiblematerial defining a flattened tube.
 17. A centrifuge assembly inaccordance with claim 16 wherein said two plies are sealed together todefine a continuously tapered height along a portion of said container.18. A centrifuge assembly in accordance with claim 16 wherein said twoplies are sealed together to define at least two container segments anda flow path communicating between said segments.
 19. A centrifugeassembly in accordance with claim 15 further comprising afluid-connection means associated with said container for removing asuspension component therefrom, said fluid connection meanscomprising:means defining an aperture in said container; means defininga filter covering said aperture; and a fluid conduit communicating withthe interior of said container through said filter means.
 20. Acentrifuge assembly in accordance with claim 19 wherein said filtermeans comprising a filter screen and said fluid conduit comprising atube attached to said container and having a plurality of perforationstherein disposed in direct communication with said filter screen, saidfluid conduit comprising a tube extending from opposite sides of saidaperture and looping together to provide a single connect tube.
 21. Acentrifuge assembly in accordance with claim 12 wherein the suspensioncomprises blood, and said channel segments contains a quantity of bloodwhich is relatively small compared to the volume of blood in a humandonor.
 22. A centrifuge assembly comprising:a rotor; a generallyannularly extending multi-portion processing channel defined in saidrotor for processing a suspension including at least one cell component,said processing channel being defined by a pair of spaced apart rigidwalls, said channel having a height substantially greater than its widthalong it a substantial length of said channel; said processing channelincluding:a first generally arcuate portion; a second portion which isgenerally spiral-like, and a transition portion of decreasing radiusrelative to a true center of said rotor, said transition portion beinglocated between said first and second portions and defining a generallyinwardly extending surface within said channel to restrict the passageof at least one suspension component between said first and secondportions.
 23. A centrifuge assembly in accordance with claim 22 furthercomprising a suspension component receiving pocket defined in at leastone of said portions.
 24. A centrifuge assembly in accordance with claim22 wherein said first portion of said processing channel is generallycircular.
 25. A centrifuge assembly in accordance with claim 22 furthercomprising fluid connection means at separated locations of said channelfor introducing the suspension into and for extracting at least onesuspension component from said channel, said fluid connection meansincluding: a first fluid connection means;communicating with saidspiral-like portion of said channel, being adapted for extracting itssuspension component from said spiral-like portion of said channel; andbeing locating at a greater radial distance from the true center of therotor than the radial distance at which the suspension component entersthe spiral-like portion of said channel.
 26. A centrifuge assembly inaccordance with claim 22 wherein said processing channel has a total arcnot greater than 360°.
 27. A centrifuge assembly in accordance withclaim 22 wherein the suspension comprises blood, and said channelcontains a quantity of blood which is relatively small compared to thevolume of blood in a human donor.
 28. A centrifuge assembly forprocessing a suspension including at least one cell componentcomprising:a rotor; a generally annularly extending multi-portionprocessing channel in said rotor; said processing channel including onegenerally annularly extending portion and another generally annularlyextending portion; said other portion of said channel being generallyspiral-like relative to the true center of said rotor; and saidprocessing channel having a total arc not greater than 360°.
 29. Acentrifuge assembly for processing a suspension including at least onecell component comprising:a rotor; a generally annularly extendingmulti-portion processing channel is said rotor; said channel includingone generally annularly extending portion and another generallyannularly extending portion; said other portion of said channel beinggenerally spiral-like relative to the true center of said rotor; andsuspension inlet and suspension component outlet connections atseparated locations of said channel, said outlet connectioncommunicatingwith said other, spiral-like portion of said channel at a greater radialdistance from the true center of the rotor than the radial distancewhere the suspension component enters said other, spiral-like portion ofsaid channel.
 30. A centrifuge assembly for processing a suspensionincluding at least one cell component comprising:a rotor; a generallyannularly extending multi-portion processing channel in said rotor; saidchannel including one generally annularly extending portion and anothergenerally annularly extending portion; said other portion of saidchannel being generally spiral-like relative to the true center of saidrotor; said multi-portion processing channel having a total arc notgreater than 360°; suspension inlet and suspension component outletconnections a separated locations along said channel; said outletconnection communicating with said other, spiral-like portion of thechannel.
 31. A centrifuge assembly for processing a suspension includingat least one cell component comprising:a rotor; a generally annularlyextending multi-portion processing channel is said rotor; said channelincluding an arcuate portion, another portion which is spiral-likerelative to the true center of said rotor, and a transition portion ofdecreasing radius relative to said true center of said rotor, saidtransition portion being located between said arcuate and spiral-likeportions of said channel and defining a generally inwardly extendingsurface within said channel; said multi-portion processing channelhaving a total arc not greater than 360°; and suspension inlet andsuspension component outlet connections at separated locations alongsaid channel; said outlet connection communicating with said spiral-likeportion of the channel at a greater radial distance from the true centerof the rotor than the radial distance where the suspension componententers said spiral-like portion of said channel.
 32. The centrifugeassembly of claim 28, 29, 30 or 31 wherein said processing channel isdefined by a pair of spaced-apart rigid vertical walls,said channelhaving a height substantially greater than its width along a substantiallength of said channel.
 33. The centrifuge assembly of claim 28, 29 or30 wherein said channel includes radially inner and outer wallsurfaces,said outer wall surface of said channel including a transitionportion of decreasing radius relative to said true center of said rotor,said transition portion being located between said one and said otherportions of said channel and defining a generally inwardly extendingsurface within said channel to restrict the flow of a suspensioncomponent between said one and other portions.
 34. The centrifugeassembly of claim 29, 30 or 31 wherein said plurality fluid connectionfurther comprises:a second fluid connection communicating with saidchannel at a location spaced from the true center of rotation of saidrotor for introducing the suspension into said channel, a third fluidconnection communicating with said one portion of said channel forremoving a second suspension component and a fourth fluid connectioncommunicating with said channel at a selected location for removinganother portion of said suspension.
 35. The centrifuge assembly of claim28, 29, 30 or 31 wherein the suspension comprises blood, and saidchannel contains a quantity of blood which is relatively small comparedto the volume of blood in a human donor.
 36. A centrifuge assembly inaccordance with claim 22, 29, 30 or 31 wherein said spiral-like portionof said channel comprises radially spaced-apart inner and outer walls,and said inner wall is generally circular relative to the true center ofsaid rotor.
 37. A centrifuge assembly in accordance with claim 29, 30 or31 wherein:said inlet connection communicates with said spiral-likeportion, said spiral-like portion of said channel comprises radiallyspaced-apart inner and outer walls, and said outer wall is ofprogressively increasing radius relative to said center of rotation in adirection from said inlet connection to said outlet connection.